Voltage sensing tool

ABSTRACT

A hand tool ( 10 ) that provides an alarm signal to a user as the tool approaches a live electrical wire is disclosed. The hand tool ( 10 ) comprises a tool head coupled to a handle. A non-contact voltage sensing circuit including an antenna is provided in the handle of the tool ( 10 ). As the tool ( 10 ) approaches a live electrical wire, the non-contact voltage sensing circuit detects the voltage, triggering an alarm circuit that provides a visual or audio signal to the user.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation in part of U.S. patent application Ser. No. 11/005,187 filed Dec. 6, 2004 and claims the benefit of the filing date of U.S. provisional patent application Ser. No. 60/700,413, filed Jul. 19, 2005.

FIELD OF INVENTION

The present invention is generally directed to an electrical sensing tool. More particularly, the present invention is directed to a hand tool that includes a non-contact voltage sensing circuit and an associated alarm circuit.

BACKGROUND

Electricians, technicians, maintenance people and others who work with and around electrical distribution and wiring systems often work in the vicinity of energized electrical panels and wires. Good practice dictates that these electrical circuits be de-energized when work is performed. Not infrequently, however, through error or oversight, these circuits remain in an energized condition during maintenance, thereby presenting an electrical hazard to both the worker and to the associated electrical equipment.

One particular hazard is encountered when conductive hand tools such as wire strippers, cutters, pliers, screwdrivers and such are employed in maintenance procedures. When these hand tools come into contact with the live electrical circuits, they can cause both injury to the worker and damage to the electrical equipment.

Due to these problems, hand held tools that include a voltage meter embedded in the handle have been developed. The voltage meter provides an indication to the user that a voltage is present on the wire and that, therefore, a live wire has been contacted. Such devices, however, require actual, physical contact with the live wire or circuit before the user is alerted. These are useful when the user is probing for a live wire. These devices, however, do not provide a sufficient warning to an unsuspecting user contacting a high voltage circuit to prevent injury or damage. Furthermore, these devices do not provide any indication of contact with a live wire when the wire is insulated.

Also available in the art are non-contact voltage indicators, also useful to probe for a live wire. These indicators provide a visual or audio indicator to the user when the indicator is placed in the vicinity of an AC voltage. An example of a device of this type is shown, for example, in U.S. Pat. No. 5,877,618 “Hand Held Non-Contact Voltage Tester”. While useful in providing an indication of a live wire, successful use of this device requires the user to test the wire before work is begun. The test, therefore, does not solve the initial problem: erroneously or mistakenly forgetting to disable or verify disablement of the circuit before work is begun.

Also known in the art are hand tool devices that include non-contact voltage sensing circuits in a handle of the tool. In these prior art devices, the tool head is constructed of a conductive material, and the non-contact voltage sensing circuit is coupled to the tool head, which acts as an antenna to pick up electrical signals from live electrical wires. These devices, again, are useful in that they allow the user to determine whether a hazardous voltage exists prior to contacting wires or cables. However, since the tool head is constructed of a metal or other conductive material, the user is required to approach electrical wires with a conductive surface. The conductive tool head, therefore, can inadvertently short circuit live wires to adjacent circuits or otherwise damage the electrical circuits being probed. Furthermore, although precautions can be taken to limit the level of voltage and current flowing into the non-contact voltage sensing circuit, a possibility of damaging the non-contact voltage sensing circuit in the tool exists when a conductive tool head is an integral part of the circuit.

SUMMARY OF THE INVENTION

The present invention is a low cost, reliable and easy-to-use hand tool providing an alert signal to a user prior to contacting a live wire. The device of the present invention integrates a non-contact voltage alert circuit and associated alarm circuitry into a hand tool, thereby providing a high degree of safety for the user. The alarm circuitry provides a visual or audio signal, alerting the user that contact with a live wire is about to be made.

In one aspect, the present invention provides a hand tool comprising a tool head, a handle operatively connected to the tool head, and a non-contact voltage sensing circuit housed in the handle. The non-contact voltage sensing circuit includes an antenna for detecting an electrical field, and an alarm circuit for generating a human perceptible alarm signal when the hand tool is in an electrical field at an elevated voltage and the antenna detects an electrical field having a voltage level above a predetermined threshold. The tool head can be, for example, a cable cutter, a wire cutter, a wire stripper, a screwdriver, a wrench, a saw blade, a blade, a crimping head, a nut driver, a conduit bender, or a pliers. Alternatively, for example, the tool head can be an axe head and a pick head.

In another aspect of the invention, the tool head comprises a non-conductive material. The non-contact voltage sensing circuit can also be electrically insulated from the tool head. The antenna can be provided inside the handle.

In another aspect of the invention, the alarm circuit includes at least one of a visual and an audio indicator device for generating the human perceptible alarm signal. A portion of the handle can include a translucent material and the human perceptible alarm circuit is a light indicator provided adjacent the translucent portion of the handle.

In still another aspect of the invention, the hand tool can be a power tool, for example a power cable cutter, power drill, power saw, power cable puller, or other power tools.

Alternatively, the tool head can be pivotally coupled to the handle, and be moveable between an extended position and a stored position. Here, the tool head can also comprise a plurality of separate tools including, for example, two of a wire cutter, a wire stripper, a screwdriver, a wrench, a blade, and a pliers.

In yet still another aspect of the invention, the handle can be constructed to include a thermoplastic rubber over mold. Furthermore, the handle can be constructed to include a cavity for receiving the non-contact voltage sensing circuit, and also to include a cavity for receiving a battery for powering the non-contact voltage sensing circuit.

In yet another aspect of the invention, the hand tool can include a tool head having a connector adapted to receive a plurality of different tool heads. For example, the tool head can include a connector adapted to accept a plurality of interchangeable screwdriver bits providing for example at least a straight blade driver and a Philips head driver.

Other features of the invention and advantages will become apparent upon reading the material provided hereafter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic plan view of a tool constructed in accordance with one embodiment of the invention

FIG. 2 is a view taken along the line 2-2 of FIG. 1;

FIG. 3 is a view taken parallel to line 3-3 of FIG. 2;

FIG. 4 is a view taken along the line 4-4 of FIG. 3;

FIG. 5 is a partial cutaway view of the hand tool of FIG. 1 showing an exploded view of the battery compartment;

FIG. 6 is a circuit diagram illustrating the non-contact voltage sensing circuit of the embodiment of FIG. 1;

FIG. 7 is a circuit diagram illustrating the use of the tool of FIG. 1;

FIG. 8 is a circuit diagram illustrating a second embodiment of a circuit diagram for a non-contact voltage sensing circuit;

FIG. 9 is perspective view of a cable cutter constricted in accordance with the present invention;

FIG. 10 is perspective view of a powered cable cutter constructed in accordance with the present invention;

FIG. 11 is a perspective view of an electricians knife constructed in accordance with the present invention;

FIG. 12 is a perspective view of a reciprocating saw constructed in accordance with the present invention;

FIG. 13 is a perspective view of a BX cutter constructed in accordance with the present invention;

FIG. 14 is a perspective view of a crimping device constructed in accordance with the present invention;

FIG. 15 is a perspective view of a pliers constructed in accordance with the present invention;

FIG. 16 is a perspective view of a wrench constructed in accordance with the present invention;

FIG. 17 is a perspective view of a screwdriver constructed in accordance with the present invention;

FIG. 18 is a perspective view of a nut runner constructed in accordance with the present invention;

FIG. 19 is a perspective view of a multi-tool constructed in accordance with the present invention;

FIG. 20 is a perspective view of an axe constructed in accordance with the present invention;

FIG. 21 is a perspective view of a conduit bender constructed in accordance with the present invention;

FIG. 22 is a perspective view of a conduit reamer constructed in accordance with the present invention; and

FIG. 23 is a perspective view of a multi-bit screwdriver constructed in accordance with the present invention.

DESCRIPTION OF THE EMBODIMENTS

Referring now to the figures and more particularly to FIG. 1, a first embodiment of a hand tool 10 constructed in accordance with the present invention is shown. The hand tool 10 generally comprises a functional tool end, hereafter the tool head 15, and one or more handles 20. As shown in FIG. 1, the hand tool 10 can be a wire cutter and stripper, wherein the head end 15 comprises first and second blade elements 11 and 13 rotatably coupled around a fastener 22. Each of the blade elements 11 and 13 comprises a blade 18 and a handle 20. The blades 18 each include a cutting edge 23 for cutting a wire. Each cutting edge 23 includes a notched cutting edge 24 which, when the blades 18 are pivoted toward each other, provide cutting edges for stripping insulation from a wire. Each of the handles 20 may be an extension of the corresponding blades and is preferably covered with a plastic grip or other non-conductive covering material 26, also as described below. A non-contact voltage alert circuit 12, which is housed in one of the handles 20, provides an alert signal to the operator to indicate that the hand tool 10 is physically approaching an electrically live wire. The blades 11 and 13 can be constructed of a non-conductive material such as plastic, although metal and other conductive materials can also be used.

Referring now also to FIG. 2, a cutaway side view of the handle 20 of the hand tool 10 of FIG. 1 taken along line 2-2 is shown. The handle 20 includes a non-contact voltage sensing circuit 12 coupled to an antenna 62 in the handle 20 and the circuit 12 is electrically isolated from the tool head 15. The handle 20 is constructed of a non-conductive material such as a plastic material 66, and the portion of the handle 20 that is intended to be gripped by a user can be encased in an outer rubber molding 68 that can be, for example, a thermoplastic rubber (TPR) or other rubberized material. An indicator portion 60 of the handle 20, here shown at the distal end of the handle 20, comprises a translucent material, such as a translucent plastic, and is positioned adjacent a light indicator such as, referring now also to FIG. 6, a light emitting diode 64 coupled to the non-contact voltage sensing circuit 12. The non-contact voltage sensing circuit 12 is retained in a cavity 74 molded or otherwise provided in the handle 20 and can include, as described below with reference to FIG. 6, a speaker or other sound transducer for emitting a sound when activated by an alarm circuit 40. The antenna 62 is further provided in the handle 20 and is coupled to an input resistor 14 of the non-contact voltage sensing circuit 12 as shown in FIG. 6 to sense an alternating current electric field. Batteries 28 for powering the circuit 12 are provided in a separate cavity 70 molded or otherwise provided in the handle 20.

Referring now to FIGS. 3, 4, and 5, the batteries 28 can be provided in an open cavity 70 formed in the handle 20 and adjacent a removable door 72 which can be, for example, snap-fit into the outer edge of the cavity 70 to provide selective access to the batteries 28. Alternatively, however, non-replaceable batteries 28 can be provided within the handle 20 and the handle 20 can be molded around the batteries 28 without providing access to the batteries.

Referring again to FIG. 6, a circuit diagram of the non-contact voltage alert circuit 12 of FIG. 1 is shown. The non-contact voltage alert circuit 12 generally comprises a trigger circuit 29 for determining when the hand tool 10 is near an energized conductor and an alarm circuit 35 for providing an indication to the user. In a preferred embodiment, the trigger circuit 29 comprises voltage divider 30; an inverter circuit 32; and a rectification circuit 34, while the alarm circuit 35 comprises a low frequency oscillator 36; a high frequency oscillator 38; and an alarm activation circuit 40.

Referring still to FIG. 6, the trigger circuit 29 receives an input alternating current (AC) voltage detected by the antenna 62, compares the input voltage to a threshold level and activates the alarm circuit 35 when the input exceeds a threshold value. The input voltage provides an indication that the hand tool 10 is near an energized wire as described below with reference to FIG. 7.

The first stage of the trigger circuit 29 is the voltage divider 30, comprising resistor 14 which receives an input voltage V₂ indicative of the proximity of the tool to a live wire, and a diode D1 coupled between the output of the resistor 14 and ground. The voltage divider 30 reduces the voltage V₂ to a level suitable for use in conjunction with the digital circuitry described below. As a function of the applied voltage V₂, the voltage across D1 varies from substantially zero when the hand tool 10 is not in proximity with a live electrical wire, to a threshold value of a few volts when the hand tool 10 is near a live wire, as described below. The value of the resistor 14 is selected to prevent excessive current flow through the non-contact voltage alert circuit 12 when the hand tool 10 touches a live wire, while also providing a relatively small voltage drop, but assuring that sufficient voltage is provided to activate the non-contact voltage alert circuit 12. For an expected input voltage provided by a wire operating in the range between 120 and 220 VAC, the resistor R1 typically has a value of 10 Mega Ohms.

The voltage across diode D1 provides an input signal to the inverter circuit 32, which comprises CMOS logic inverter gates 1A and 1B. The gate 1A switches between a logic high and a logic low state as the voltage across the diode D1 reaches a threshold value, typically in a range between one and two volts. As noted above, the voltage across D1 and, therefore, the input voltage to the inverter 1A varies with the distance between the hand tool 10 and a live electrical wire. When the hand tool 10 is not near a live wire, the voltage across diode D1 is substantially zero and therefore below the threshold voltage. In this state, the output of inverter gate 1A will be high because of the inverting action of the logic gate. When the hand tool 10 is placed near a live wire with a voltage impressed on it, the voltage across D1 rises above the threshold voltage to trip the inverter 1A causing the output of inverter 1A to go low. A logic low output from inverter 1A therefore indicates that a voltage is being sensed by the hand tool 10. The second inverter, 1B, buffers and inverts the signal, thereby providing a logic high output signal from the inverter circuit 34 when the tool 10 is near a live wire.

The output of inverter 1B is received by the rectifying circuit 34, which converts the alternating voltage signal to a direct current (DC) voltage using a typical rectifying circuit comprising diode D2, resistor R2, and capacitor C1. The rectifying circuit 34 provides a DC voltage across capacitor C1, therefore, only when the hand tool 10 is near an energized live wire.

The output of the rectifying circuit 34 is received by the alarm circuit 35, which provides a visual or audio signal to the user, as described below. In a preferred embodiment of the invention, the alarm circuit comprises low and high frequency oscillator circuits 36 and 38.

The low frequency oscillator circuit 36 comprises logic inverters 1C and 1D, along with associated components D3, R3, R4, and C2. The low frequency oscillator circuit 36 is activated or enabled when a DC voltage is present on capacitor C1. When activated, the low frequency oscillator produces an output signal having a frequency in the range of 1 to 5 Hertz.

The output signal of the low frequency circuit 36 enables the high frequency oscillator 38, comprising logic inverters 1E and 1F and the associated components R6, D4, R5, and C3. The high frequency oscillator 38 produces an output signal in an audio frequency range. The output of the oscillator 38 drives the alarm activation circuit 40 by activating transistor TR1, which in turn is connected to a speaker SPKR and an LED. Hence, when the hand tool 10 is placed near an energized WIRE, the LED is activated and the speaker will produce a sound in the audio range produced by the oscillator 38.

Although the alarm circuit 35 has been described to include oscillators 36 and 38, a number of different alarm circuits can be constructed to provide similar functions. For example, if only a visual indicator such as the LED is used, a transistor switch to an LED can be used. Other alarm circuits will be apparent to those of ordinary skill in the art.

As described above, the circuit 12 of FIG. 6 includes low powered CMOS devices that can be constantly energized by the batteries 28, as the batteries can last a long time. In an alternate embodiment shown in FIG. 8, the voltage alert circuit 12 is activated by a switch 16 which applies power from the battery 28 to the circuit 12. Here, the negative terminal of the battery 28 is connected to circuit common or ground through a switch 16 and, therefore, the switch 16 must be activated to energize the circuit. In embodiments that use a non-contact voltage sensing circuit 12 including a switch 16, the switch 16 can be provided on the handle 20 of the hand tool 10. When the user's hand pushes switch 16, it energizes the alert circuit 12, thereby enabling the alarm circuit 35 to be activated. The switch 16 also provides an electrical path from the circuit common or ground to the user's body and through the user down to the ground.

Referring now to FIG. 7, in operation a user 44 grips the handles 20 of the hand tool 10 in a hand 46 to cut or strip insulation from a wire 52. The wire 52 is electrically coupled to a voltage source 54 provided between the wire 52 and ground 50. The voltage source 54 is typical of those encountered in home or business electrical wiring, and can be, for example, a voltage supply operating in the range of 120 or 220 volts AC at either 50 or 60 Hertz, or in various other voltage source configurations used in electrical supply configurations. As the hand tool 10 approaches the energized wire, the user 44 is coupled to the energized wire 52 through a first impedance 58 caused by the air gap between the energized wire 52 and a second impedance 56 from the resistor 14 and the non-contact voltage circuit 12 in the insulated handle of the tool. The user 44 is further coupled to ground 50 through an impedance 48 comprising generally an impedance from the shoes of the user 44 and the floor of the installation environment. Therefore, a complete circuit exists from the power source 54, through the wire 52, through the air to the tool 10, from the antenna 12 of the tool 10 to the user 44 and through the user 44 to ground 50, which is the ground of the voltage source 54.

Based on Kirchoff's law, which states that the sum of the voltage rises (sources) must equal the sum of the voltage drops around a closed loop circuit, the voltage drops across the impedances 48 (V3), 56 (V2), and 58 (V1) add to be substantially equivalent to that of the voltage source 54 (Vs), such that Vs=V1+V2+V3. Here, the voltage drop across the body of the user 44 is neglected, as the impedance of the human body is comparatively very low. It should be clear from FIG. 5 that the impedances 58, 56, and 48 and the associated voltage drops V1, V2, and V3 can vary widely as the hand tool 10 is moved about in the vicinity of the wire 52.

If the hand tool 10 is far from the wire 52, the voltage V1 is substantially equivalent to that of the voltage source 54 because the impedance 58 of the air gap is much larger than that of the other impedances. As the hand tool 10 is moved closer to the wire 52, the impedance 58 becomes smaller and current begins to flow in the circuit. Because the impedance 56 across the hand tool 10, and particularly input resistor 14, is large, a voltage drop V2 will occur. As the voltage drop V2 rises above a threshold level, the trigger circuit 29 of the non-contact voltage alert circuit 12 will be activated as described above, thereby causing visual and/or audible signals to be provided to the user 44.

If the hand tool 10 touches the wire 52, V1 becomes small and most of the voltage 54 is across the hand tool impedance 56 and floor impedance 48. To prevent a hazard to the user 44 under such circumstances, the impedance 56 of the hand tool 10, and particularly resistor 14, is selected to prevent a large current flow, as described above. Although the wire 52 has been described as an insulated wire, the wire 52 can also be a bare wire, without requiring a change to the sensing circuit.

Referring again to FIG. 1, a second example of the operation of the hand tool 10 is shown. Here, when the handle 20 is positioned near a live electrical AC power supply, such as the electrical outlet shown, the antenna 62 in the handle 20 detects the AC electrical signal that is then directed to the non-contact voltage sensing circuit 12. The non-contact voltage circuit 12 compares the voltage detected by the antenna 62 to a threshold value as described above with reference to FIG. 6, and activates an alarm circuit 40 for providing an indication to the user. As shown, the circuit 12 activates at least one of the light indicator LED 64 or the SPKR provided in the non-contact voltage sensing circuit 12 (FIG. 6). When the LED 64 is activated, the indicator light provides a signal to the user through the translucent indicator portion 60 of the handle 20. By providing the antenna 62 in the handle 20, the voltage sensing circuit 12 can operate without the need to connect the circuit to the tool head. Therefore, the tool head 15 can be constructed of a non-conductive material, such as a plastic. Furthermore, the non-contact voltage sensing circuit 12 is isolated from the tool head 15, thereby limiting the possibility of damage.

Although the hand tool 10 has been described as a wire cutter and stripper, other types of hand and power tools can be provided with a non-contact voltage sensing circuit 12 as described above. Additionally, although specific embodiments of the non-contact voltage alert circuit 12 have been described, it will be apparent that various types of alert and alarm circuitry can be employed.

Although the LED 64 is described above as being located adjacent a translucent plastic material and molded within the handle 20 itself, it will be apparent that a light indicator could also be provided outside of the handle 20, or connected to the hand tool 10 in various other ways. Furthermore, various methods of providing a battery cavity 70 in the handle and an adjacent access door 72 will also be apparent. Although the construction has been described above as being plastic, various other materials will be suitable for application in the hand tool 10. Although the tool head 15 can be constructed of a non-conductive material, as the circuit is isolated from the tool head, conductive materials can also be used.

As described above, the present invention has application in a number of types of tools for cutting and stripping wire, including wire cutters and wire strippers (FIG. 1). The present invention also has application to a large number of other cutting devices including cutters for large cables, ratcheting cable cutters, scissors, or shears, which are typically configured using blades as discussed above with reference to the wire stripper of FIG. 1. For example, a hand tool 10 comprising a tool head 15 in the form of a cable cutter is shown in FIG. 9. An indicator portion 60 of the handle 20 provides a signal when the cutter is near a live voltage. Referring now to FIG. 10, in addition to the manual cable cutter of FIG. 9, powered cable cutters, such as those that are powered hydraulically can also be used. Cable cutters that are powered pneumatically, electrically, or in other ways are also contemplated.

In addition, the present invention can be applied to cutting devices including a single blade, such as an electrician's knife as shown in FIG. 11. Here, the tool 10 includes a tool head 15 comprising a single foldable blade, a handle 20 including a non-contact voltage sensing circuit 12, and an indicator 60. Referring now to FIG. 12, the invention can also be provided in a power tool, such as a reciprocating saw which, as shown, includes a tool head 15 coupled to a handle 20 including the non-contact voltage sensing circuit 12 and indicator or alarm 60. Referring now to FIG. 13, a non-contact voltage sensing circuit 12 can also be provided in a handle 20 of a cutting device including a tool head 15 comprising a circular blade, such as a BX cutter or other similar devices for cutting AC type or armored cable.

In addition to devices for stripping and/or cutting electric cables and other substances, referring now to FIG. 14, the present invention also has application to crimping devices for crimping connectors onto cables and/or crimping cables or wires together. Here, the tool head 15 includes a crimping head which receives a connecting device and applies pressure to the crimping device and wires or cable positioned in the hand tool 10 when a squeezing pressure is applied to the handles 20. Although the crimping device shown is a manual crimping device, the present invention can be used in conjunction with both manual crimping tools and powered or high pressure crimping tools, including those that are operated electrically and through hydraulic and/or pneumatic circuits.

As described above, the present invention can also be applied in a number of common tools including wrenches, pliers, screwdrivers, and nut runners. Referring now to FIG. 15, a tool 10 including a tool head 15 comprising a pliers is shown. A handle 20 includes a non-contact voltage sensing circuit 12 and an alarm indicator 60. Referring now to FIGS. 16, 17, and 18, the present invention is shown as incorporated in a wrench, a screwdriver, and a nut driver, respectively. Suitable wrenches include socket wrenches, pipe, and connector wrenches. Screwdrivers can include Phillips, straight blade, and other types of screwdrivers. Referring now to FIG. 23, the tool head 15 can also comprise a connector 80 adapted to receive interchangeable bits 82 and 84 including different kinds of blades. These types of devices, also known as multi-bit screwdrivers, are well known in the art. Furthermore, although manual devices are shown, it will be apparent that the present invention could also be employed in power tools such as a power screwdriver or drill which include power circuits for driving the tool head 15. The power circuits, as discussed above, can be electric, hydraulic, or pneumatic.

Referring now to FIG. 19, the present invention can also be used in conjunction with multi-tool devices including a handle 20 and one or more tool head 15 pivotably mounted to fold into the handle 20. As shown here, the tool head 15 comprises a cutting blade 17, a straight blade screwdriver 19, a Phillips head screwdriver 23, and a scissors 25. Various other configurations will be apparent to those of skill in the art, and could include virtually any of the tool heads described herein. As described above with reference to the electrician's knife of FIG. 11, the tool heads here are each foldable between an extended and a stored position. Other types of foldable tools, such as Allen wrenches, are also contemplated.

Referring now to FIG. 20, the present invention can also be provided in an axe or pick. This configuration provides a tool that is particularly useful in emergency situations, and can be used by police or firefighters to locate downed electrical wires and other hazards.

The present invention may also be employed on various types of tools used by electricians and in or around electrical conductors. Referring now to FIGS. 21 and 22, respectively, a non-contact voltage sensing circuit 12 can be provided in the handle 20 of a tool 10 including a conduit bender as a tool head 15, and in hand tools 10 including a conduit reamer for the tool head 15. The conduit reamer can also be removably provided on a tool such as a screwdriver (FIG. 17).

Although the invention has been described above as useful in conjunction with a number of general purpose and electrician's tools, tools for specific purposes, such as tools specific for data communication applications (datacom tools), can also be constructed to include a non-contact voltage sensing circuit 12. For example, datacom cable strippers, cutters, and pliers, insertion and extraction tools, and other types of devices can all be constructed as described above.

Although preferred embodiments have been shown and described, it will be apparent to one of ordinary skill in the art that a number of modifications could be made to the method and apparatus described without departing from the scope of the invention. For example, although the term “hand tool” has been used, as described above, the present invention has application to power as well as manual hand tools, and the term “hand tool” is intended to include both manual and power-driven devices. Furthermore, although a number of specific embodiments are described, it will be apparent that the present invention can be provided in any number of different tools that are generally configured to use with a handle section and a tool head. Additionally, although the indicator has been described and shown as being provided internally in a portion of the handle, it will be apparent that indicators can be provided throughout the handle, as part of the tool head, external to the handle, or in other ways. Furthermore, although a sound and light indicator have been described, vibrational indicators and other devices could also be used. Additionally, although a tool head including a connector for receiving multiple screw heads has been described above, it will be apparent that connectors useful with other types of tool heads, including socket wrenches, can also be used. It should be understood, therefore, that the methods and apparatuses described above are only illustrative and do not limit the scope of the invention, and that various modifications could be made by those skilled in the art that would fall within the scope of the invention. 

1. A hand tool, comprising: a tool head; a handle operatively connected to the tool head; and a non-contact voltage sensing circuit housed in the handle, the non-contact voltage sensing circuit including an antenna extending toward an end of the handle opposite the tool head for detecting an electrical field, and an alarm circuit for generating a human perceptible alarm signal when the hand tool is in an electrical field at an elevated voltage and the antenna detects an electrical field having a voltage level above a predetermined threshold.
 2. The hand tool as defined in claim 1, wherein the non-contact voltage sensing circuit is electrically insulated from the tool head.
 3. The hand tool as defined in claim 1, wherein the tool head comprises a non-conductive material.
 4. The hand tool as defined in claim 1, wherein the antenna is inside of the handle.
 5. The hand tool as defined in claim 1, wherein the alarm circuit includes at least one of a visual and an audio indicator device for generating the human perceptible alarm signal.
 6. The hand tool as defined in claim 1, wherein at least a portion of the handle includes a translucent material and the human perceptible alarm circuit is a light indicator provided adjacent the translucent portion of the handle.
 7. The hand tool as defined in claim 6, wherein the light indicator is provided adjacent an end of the handle opposite the tool head.
 8. The hand tool as defined in claim 1, wherein the handle is formed to include a cavity for receiving the non-contact voltage sensing circuit.
 9. The hand tool as defined in claim 1, wherein the handle is formed to include a light indicator at an end opposite the tool head.
 10. The hand tool as defined in claim 1, wherein the tool head is at least one of a cable cutter, a wire cutter, a wire stripper, a screwdriver, a wrench, a saw blade, a blade, a crimping head, a nut driver, a conduit bender, and a pliers.
 11. The hand tool as defined in claim 1, further comprising a power circuit for operating the tool head.
 12. The hand tool as defined in claim 1, wherein the tool head is pivotally coupled to the handle, and wherein the tool head is moveable between an extended position and a stored position.
 13. The hand tool as defined in claim 1, wherein the tool head comprises a plurality of tool heads and includes at least two of a wire cutter, a wire stripper, a screwdriver, a wrench, a blade, and a pliers.
 14. The hand tool as defined in claim 1, wherein the tool head includes a connector adapted to receive a plurality of interchangeable tool heads.
 15. The hand tool as defined in claim 1, wherein the tool head is a screwdriver and the screwdriver is adapted to accept a plurality of interchangeable bits providing at least a straight blade driver and a Philips head driver.
 16. The hand tool as defined in claim 1, wherein the tool head is at least one of an axe head and a pick head.
 17. The hand tool as defined in claim 1, wherein the tool head comprises a conduit reamer.
 18. The tool head as defined in claim 1, wherein the tool head comprises a conductive material.
 19. A hand tool, comprising: a tool head; a handle operatively connected to the tool head and including a light indicator at a distal end of the handle opposite the tool head; and a non-contact voltage sensing circuit housed in the handle, the non-contact voltage sensing circuit including an antenna for detecting an electrical field, and an alarm circuit for activating the light indicator when the hand tool is in an electrical field at an elevated voltage and the antenna detects an electrical field having a voltage level above a predetermined threshold.
 20. The hand tool as defined in claim 19, wherein the non-contact voltage sensing circuit is electrically insulated from the tool head.
 21. The hand tool as defined in claim 19, wherein the tool head comprises a non-conductive material.
 22. The hand tool as defined in claim 19, wherein the antenna is inside of the handle and directed toward the distal end of the handle opposite the tool head.
 23. The hand tool as defined in claim 19, wherein at least a portion of the handle includes a translucent material and the light indicator is provided adjacent the translucent portion of the handle.
 24. The hand tool as defined in claim 19, wherein the handle is formed to include a cavity for receiving the non-contact voltage sensing circuit.
 25. The hand tool as defined in claim 19, wherein the tool head is at least one of a cable cutter, a wire cutter, a wire stripper, a screwdriver, a wrench, a saw blade, a blade, a crimping head, a nut driver, a conduit bender, and a pliers.
 26. The hand tool as defined in claim 19, wherein the tool head is pivotally coupled to the handle, and wherein the tool head is moveable between an extended position and a stored position.
 27. The hand tool as defined in claim 19, wherein the tool head comprises a plurality of tool heads and includes at least two of a wire cutter, a wire stripper, a screwdriver, a wrench, a blade, and a pliers.
 28. The hand tool as defined in claim 19, wherein the tool head includes a connector adapted to receive a plurality of interchangeable tool heads.
 29. The hand tool as defined in claim 19, wherein the tool head is a screwdriver and the screwdriver is adapted to accept a plurality of interchangeable bits providing at least a straight blade driver and a Philips head driver.
 30. The hand tool as defined in claim 19, wherein the tool head is at least one of an axe head and a pick head.
 31. The hand tool as defined in claim 19, wherein the tool head comprises a conduit reamer.
 32. The tool head as defined in claim 19, wherein the tool head comprises a conductive material.
 33. A hand tool, comprising: a tool head; a handle operatively connected to the tool head and including a light indicator at a distal end opposite the tool head; and a non-contact voltage sensing circuit housed in the handle, the non-contact voltage sensing circuit being electrically isolated from the tool head and including an antenna provided in the handle adjacent the end of the handle opposite the tool head for detecting an electrical field, and an alarm circuit for activating the light indicator when the hand tool is in an electrical field at an elevated voltage and the antenna detects an electrical field having a voltage level above a predetermined threshold. 